1. Field of the Invention
The present invention relates to a wireless access system and, more particularly, to a method and apparatus for performing device-to-device (D2D) client cooperation.
2. Related Art
Standardization for a cooperative-MIMO (CO-MIMO) and a signal transmission through a relay or femto cell in an IEEE 802.16m system or LTE (-A) system is in progress to enhance transmission efficiency and throughput of mobile stations (MSs) with poor channel status among MSs positioned in a cell.
Further, besides methods of supporting MSs using a base station or a femto cell or relay that operates as a base station as described above, research for cooperative communication (e.g., mobile relaying) that transmits signals through cooperation between MSs or a client cooperation (CC) is recently underway for the 802.16 systems or LTE (-A) systems.
Current cellular wireless transmission systems define transmission/reception methods between a base station and an MS. In such case, the base station may transmit signals to the MS using a femto BS or relay station (RS) so as to effectively transmit signals to the MS.
In the foregoing, the femto-BS or RS plays a role as a base station. In the current IEEE 802.16 and 3GPP LTE/LTE-A standards, signal transmission over links between BS (or femto-BS)-MS, BS-RS, and MS-RS are being actively standardized.
However, more research is being conducted not only on device-to-device communication between the human type device (HTC), but also on device-to-device communication between machine type devices (MTCs) with increasing demand for lower power consumption, transmission reliability, or enhanced throughput.